This invention relates generally to display units, and more particularly, to a large display unit which is used outdoors for advertisements, announcements, or the like.
A conventional large display unit for outdoor use is known which includes a display panel made of a hard metal or resin and formed with display windows arranged in, for example, a 24.times.24 matrix. A printed circuit board is mounted on the back of the display panel and includes a plurality of light emitting diodes (LEDs) mounted thereon in correspondence with the display windows. A driver circuit board is mounted behind the printed circuit board. The driver circuit board receives a character code from an external circuit and converts it into drive signals which are supplied to the light emitting diodes. As a result, only certain ones of the light emitting diodes are illuminated. Each display unit is adapted to display a single character. Accordingly, a plurality of display units are arranged in order to display a message, with each display unit displaying a single character.
Since each display unit is primarily intended to be used outdoors, it is housed within a waterproof casing having a waterproof electrical connector for receiving the character code from the aforementioned external circuit. Since the display windows ar covered with glass or the like so as to seal the windows from the external environment, the entire structure of the display unit and casing is made waterproof.
However, such conventional display unit is disadvantageous for various reasons.
First, the weight and volume of each display unit is large so that transportation and maintenance of the display unit becomes difficult.
Secondly, because of the large weight of the display unit, a large frame is required to mount the display unit, resulting in a semi-permanent installation. In other words, such display units are not suitable for temporary use such as in entertainment applications, or at parties, meetings, or the like. Also, because of the large frame, transportation is difficult.
Third, because of the semi-permanent installation, measures to cope with damage from wind and other environmental elements become necessary, resulting in an expensive mounting frame.
Fourth, it will be appreciated that, because of the weight of the display units, and thereby the strong mounting frame that is required, it is impossible to make a display unit larger than approximately 90.times.90 cm. Since the display units cannot be made of a sufficiently large size, it is difficult to clearly recognize a displayed character from a remote position and to attract viewers when the display unit is used outdoors.